A door set generally comprises at least one door knob rotatable in a housing structure adapted to be mounted on a door and coupled by an actuating formation, generally referred to as eccentric formation or eccentric pin, with the bolt of a bolt assembly extending through the edge of the door to permit the head of the bolt to emerge from this assembly and engage a strike in a door post.
The bolt assembly can include a sleeve which extends through a bore in the edge of the door meeting the bore in which the housing is mounted and a spring which can be provided in the sleeve to urge the head of the bolt within the sleeve into engagement with the strike. This spring can be a coil spring. The bolt assembly can be coupled by an end of its shank to the eccentric pin connected to the door knob so that the arcuate movement of the eccentric pin will be translated into a linear displacement of the bolt against the force of the spring when the door know is rotated to draw the bolt head out of a strike.
It has been proposed to provide this connecting element as a hook which is formed as part of the bolt pin. This not only has the disadvantage that fabrication of the one piece bolt pin is complex and expensive, but also the drawback that axial adjustment of the distance between the bolt head or the effective end of the bolt and the eccentric pin is not possible.
The latter disadvantage is particularly acute when it is understood that frequently the center of rotation of the door knob may not be precisely located with respect to the edge of the door as may be desired.
Austrian patent No. 375,722, therefore, teaches an improvement in which the connecting hook is tied to the bolt pin or bolt head by a screw, the latter extending longitudinally through the bolt and allowing a swinging movement of the hook which is nevertheless precluded from rotating once the axial positions are established.
In this construction, the screw extends the full length of the bolt so that it can be adjusted from an end of the bolt. Between the bolt and the connecting hook a spacer compression spring can be provided. This assembly permits the position of the hook and hence the location of the eccentric pin to be adjusted relative to the strike.
This arrangement, of course, is able to overcome the drawback of nonadjustability mentioned earlier and also has the advantage that the hook is subjected to little bending stress. However, it has the important disadvantage that it is made up of many parts, namely, the bolt itself, the hook, the screw, the associated support washer and the spacer compression spring. Not only is this problematical because assembly is time consuming and misplacing of a part may render the entire unit useless, but the fabrication costs of such a door set are inordinately increased by the excess number of parts and the need to assemble them.